/* * lib/bitmap.c * Helper functions for bitmap.h. * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */#include <linux/export.h>#include <linux/thread_info.h>#include <linux/ctype.h>#include <linux/errno.h>#include <linux/bitmap.h>#include <linux/bitops.h>#include <linux/bug.h>#include <asm/page.h>#include <asm/uaccess.h>/* * bitmaps provide an array of bits, implemented using an an * array of unsigned longs. The number of valid bits in a * given bitmap does _not_ need to be an exact multiple of * BITS_PER_LONG. * * The possible unused bits in the last, partially used word * of a bitmap are 'don't care'. The implementation makes * no particular effort to keep them zero. It ensures that * their value will not affect the results of any operation. * The bitmap operations that return Boolean (bitmap_empty, * for example) or scalar (bitmap_weight, for example) results * carefully filter out these unused bits from impacting their * results. * * These operations actually hold to a slightly stronger rule: * if you don't input any bitmaps to these ops that have some * unused bits set, then they won't output any set unused bits * in output bitmaps. * * The byte ordering of bitmaps is more natural on little * endian architectures. See the big-endian headers * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h * for the best explanations of this ordering. */int__bitmap_equal(constunsignedlong*bitmap1,constunsignedlong*bitmap2,unsignedintbits){unsignedintk,lim=bits/BITS_PER_LONG;for(k=0;k<lim;++k)if(bitmap1[k]!=bitmap2[k])return0;if(bits%BITS_PER_LONG)if((bitmap1[k]^bitmap2[k])&BITMAP_LAST_WORD_MASK(bits))return0;return1;}EXPORT_SYMBOL(__bitmap_equal);void__bitmap_complement(unsignedlong*dst,constunsignedlong*src,unsignedintbits){unsignedintk,lim=bits/BITS_PER_LONG;for(k=0;k<lim;++k)dst[k]=~src[k];if(bits%BITS_PER_LONG)dst[k]=~src[k];}EXPORT_SYMBOL(__bitmap_complement);/** * __bitmap_shift_right - logical right shift of the bits in a bitmap * @dst : destination bitmap * @src : source bitmap * @shift : shift by this many bits * @nbits : bitmap size, in bits * * Shifting right (dividing) means moving bits in the MS -> LS bit * direction. Zeros are fed into the vacated MS positions and the * LS bits shifted off the bottom are lost. */void__bitmap_shift_right(unsignedlong*dst,constunsignedlong*src,unsignedshift,unsignednbits){unsignedk,lim=BITS_TO_LONGS(nbits);unsignedoff=shift/BITS_PER_LONG,rem=shift%BITS_PER_LONG;unsignedlongmask=BITMAP_LAST_WORD_MASK(nbits);for(k=0;off+k<lim;++k){unsignedlongupper,lower;/* * If shift is not word aligned, take lower rem bits of * word above and make them the top rem bits of result. */if(!rem||off+k+1>=lim)upper=0;else{upper=src[off+k+1];if(off+k+1==lim-1)upper&=mask;upper<<=(BITS_PER_LONG-rem);}lower=src[off+k];if(off+k==lim-1)lower&=mask;lower>>=rem;dst[k]=lower|upper;}if(off)memset(&dst[lim-off],0,off*sizeof(unsignedlong));}EXPORT_SYMBOL(__bitmap_shift_right);/** * __bitmap_shift_left - logical left shift of the bits in a bitmap * @dst : destination bitmap * @src : source bitmap * @shift : shift by this many bits * @nbits : bitmap size, in bits * * Shifting left (multiplying) means moving bits in the LS -> MS * direction. Zeros are fed into the vacated LS bit positions * and those MS bits shifted off the top are lost. */void__bitmap_shift_left(unsignedlong*dst,constunsignedlong*src,unsignedintshift,unsignedintnbits){intk;unsignedintlim=BITS_TO_LONGS(nbits);unsignedintoff=shift/BITS_PER_LONG,rem=shift%BITS_PER_LONG;for(k=lim-off-1;k>=0;--k){unsignedlongupper,lower;/* * If shift is not word aligned, take upper rem bits of * word below and make them the bottom rem bits of result. */if(rem&&k>0)lower=src[k-1]>>(BITS_PER_LONG-rem);elselower=0;upper=src[k]<<rem;dst[k+off]=lower|upper;}if(off)memset(dst,0,off*sizeof(unsignedlong));}EXPORT_SYMBOL(__bitmap_shift_left);int__bitmap_and(unsignedlong*dst,constunsignedlong*bitmap1,constunsignedlong*bitmap2,unsignedintbits){unsignedintk;unsignedintlim=bits/BITS_PER_LONG;unsignedlongresult=0;for(k=0;k<lim;k++)result|=(dst[k]=bitmap1[k]&bitmap2[k]);if(bits%BITS_PER_LONG)result|=(dst[k]=bitmap1[k]&bitmap2[k]&BITMAP_LAST_WORD_MASK(bits));returnresult!=0;}EXPORT_SYMBOL(__bitmap_and);void__bitmap_or(unsignedlong*dst,constunsignedlong*bitmap1,constunsignedlong*bitmap2,unsignedintbits){unsignedintk;unsignedintnr=BITS_TO_LONGS(bits);for(k=0;k<nr;k++)dst[k]=bitmap1[k]|bitmap2[k];}EXPORT_SYMBOL(__bitmap_or);void__bitmap_xor(unsignedlong*dst,constunsignedlong*bitmap1,constunsignedlong*bitmap2,unsignedintbits){unsignedintk;unsignedintnr=BITS_TO_LONGS(bits);for(k=0;k<nr;k++)dst[k]=bitmap1[k]^bitmap2[k];}EXPORT_SYMBOL(__bitmap_xor);int__bitmap_andnot(unsignedlong*dst,constunsignedlong*bitmap1,constunsignedlong*bitmap2,unsignedintbits){unsignedintk;unsignedintlim=bits/BITS_PER_LONG;unsignedlongresult=0;for(k=0;k<lim;k++)result|=(dst[k]=bitmap1[k]&~bitmap2[k]);if(bits%BITS_PER_LONG)result|=(dst[k]=bitmap1[k]&~bitmap2[k]&BITMAP_LAST_WORD_MASK(bits));returnresult!=0;}EXPORT_SYMBOL(__bitmap_andnot);int__bitmap_intersects(constunsignedlong*bitmap1,constunsignedlong*bitmap2,unsignedintbits){unsignedintk,lim=bits/BITS_PER_LONG;for(k=0;k<lim;++k)if(bitmap1[k]&bitmap2[k])return1;if(bits%BITS_PER_LONG)if((bitmap1[k]&bitmap2[k])&BITMAP_LAST_WORD_MASK(bits))return1;return0;}EXPORT_SYMBOL(__bitmap_intersects);int__bitmap_subset(constunsignedlong*bitmap1,constunsignedlong*bitmap2,unsignedintbits){unsignedintk,lim=bits/BITS_PER_LONG;for(k=0;k<lim;++k)if(bitmap1[k]&~bitmap2[k])return0;if(bits%BITS_PER_LONG)if((bitmap1[k]&~bitmap2[k])&BITMAP_LAST_WORD_MASK(bits))return0;return1;}EXPORT_SYMBOL(__bitmap_subset);int__bitmap_weight(constunsignedlong*bitmap,unsignedintbits){unsignedintk,lim=bits/BITS_PER_LONG;intw=0;for(k=0;k<lim;k++)w+=hweight_long(bitmap[k]);if(bits%BITS_PER_LONG)w+=hweight_long(bitmap[k]&BITMAP_LAST_WORD_MASK(bits));returnw;}EXPORT_SYMBOL(__bitmap_weight);voidbitmap_set(unsignedlong*map,unsignedintstart,intlen){unsignedlong*p=map+BIT_WORD(start);constunsignedintsize=start+len;intbits_to_set=BITS_PER_LONG-(start%BITS_PER_LONG);unsignedlongmask_to_set=BITMAP_FIRST_WORD_MASK(start);while(len-bits_to_set>=0){*p|=mask_to_set;len-=bits_to_set;bits_to_set=BITS_PER_LONG;mask_to_set=~0UL;p++;}if(len){mask_to_set&=BITMAP_LAST_WORD_MASK(size);*p|=mask_to_set;}}EXPORT_SYMBOL(bitmap_set);voidbitmap_clear(unsignedlong*map,unsignedintstart,intlen){unsignedlong*p=map+BIT_WORD(start);constunsignedintsize=start+len;intbits_to_clear=BITS_PER_LONG-(start%BITS_PER_LONG);unsignedlongmask_to_clear=BITMAP_FIRST_WORD_MASK(start);while(len-bits_to_clear>=0){*p&=~mask_to_clear;len-=bits_to_clear;bits_to_clear=BITS_PER_LONG;mask_to_clear=~0UL;p++;}if(len){mask_to_clear&=BITMAP_LAST_WORD_MASK(size);*p&=~mask_to_clear;}}EXPORT_SYMBOL(bitmap_clear);/** * bitmap_find_next_zero_area_off - find a contiguous aligned zero area * @map: The address to base the search on * @size: The bitmap size in bits * @start: The bitnumber to start searching at * @nr: The number of zeroed bits we're looking for * @align_mask: Alignment mask for zero area * @align_offset: Alignment offset for zero area. * * The @align_mask should be one less than a power of 2; the effect is that * the bit offset of all zero areas this function finds plus @align_offset * is multiple of that power of 2. */unsignedlongbitmap_find_next_zero_area_off(unsignedlong*map,unsignedlongsize,unsignedlongstart,unsignedintnr,unsignedlongalign_mask,unsignedlongalign_offset){unsignedlongindex,end,i;again:index=find_next_zero_bit(map,size,start);/* Align allocation */index=__ALIGN_MASK(index+align_offset,align_mask)-align_offset;end=index+nr;if(end>size)returnend;i=find_next_bit(map,end,index);if(i<end){start=i+1;gotoagain;}returnindex;}EXPORT_SYMBOL(bitmap_find_next_zero_area_off);/* * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers, * second version by Paul Jackson, third by Joe Korty. */#define CHUNKSZ 32#define nbits_to_hold_value(val) fls(val)#define BASEDEC 10 /* fancier cpuset lists input in decimal *//** * __bitmap_parse - convert an ASCII hex string into a bitmap. * @buf: pointer to buffer containing string. * @buflen: buffer size in bytes. If string is smaller than this * then it must be terminated with a \0. * @is_user: location of buffer, 0 indicates kernel space * @maskp: pointer to bitmap array that will contain result. * @nmaskbits: size of bitmap, in bits. * * Commas group hex digits into chunks. Each chunk defines exactly 32 * bits of the resultant bitmask. No chunk may specify a value larger * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value * then leading 0-bits are prepended. %-EINVAL is returned for illegal * characters and for grouping errors such as "1,,5", ",44", "," and "". * Leading and trailing whitespace accepted, but not embedded whitespace. */int__bitmap_parse(constchar*buf,unsignedintbuflen,intis_user,unsignedlong*maskp,intnmaskbits){intc,old_c,totaldigits,ndigits,nchunks,nbits;u32chunk;constchar__user__force*ubuf=(constchar__user__force*)buf;bitmap_zero(maskp,nmaskbits);nchunks=nbits=totaldigits=c=0;do{chunk=ndigits=0;/* Get the next chunk of the bitmap */while(buflen){old_c=c;if(is_user){if(__get_user(c,ubuf++))return-EFAULT;}elsec=*buf++;buflen--;if(isspace(c))continue;/* * If the last character was a space and the current * character isn't '\0', we've got embedded whitespace. * This is a no-no, so throw an error. */if(totaldigits&&c&&isspace(old_c))return-EINVAL;/* A '\0' or a ',' signal the end of the chunk */if(c=='\0'||c==',')break;if(!isxdigit(c))return-EINVAL;/* * Make sure there are at least 4 free bits in 'chunk'. * If not, this hexdigit will overflow 'chunk', so * throw an error. */if(chunk&~((1UL<<(CHUNKSZ-4))-1))return-EOVERFLOW;chunk=(chunk<<4)|hex_to_bin(c);ndigits++;totaldigits++;}if(ndigits==0)return-EINVAL;if(nchunks==0&&chunk==0)continue;__bitmap_shift_left(maskp,maskp,CHUNKSZ,nmaskbits);*maskp|=chunk;nchunks++;nbits+=(nchunks==1)?nbits_to_hold_value(chunk):CHUNKSZ;if(nbits>nmaskbits)return-EOVERFLOW;}while(buflen&&c==',');return0;}EXPORT_SYMBOL(__bitmap_parse);/** * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap * * @ubuf: pointer to user buffer containing string. * @ulen: buffer size in bytes. If string is smaller than this * then it must be terminated with a \0. * @maskp: pointer to bitmap array that will contain result. * @nmaskbits: size of bitmap, in bits. * * Wrapper for __bitmap_parse(), providing it with user buffer. * * We cannot have this as an inline function in bitmap.h because it needs * linux/uaccess.h to get the access_ok() declaration and this causes * cyclic dependencies. */intbitmap_parse_user(constchar__user*ubuf,unsignedintulen,unsignedlong*maskp,intnmaskbits){if(!access_ok(VERIFY_READ,ubuf,ulen))return-EFAULT;return__bitmap_parse((constchar__force*)ubuf,ulen,1,maskp,nmaskbits);}EXPORT_SYMBOL(bitmap_parse_user);/** * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string * @list: indicates whether the bitmap must be list * @buf: page aligned buffer into which string is placed * @maskp: pointer to bitmap to convert * @nmaskbits: size of bitmap, in bits * * Output format is a comma-separated list of decimal numbers and * ranges if list is specified or hex digits grouped into comma-separated * sets of 8 digits/set. Returns the number of characters written to buf. * * It is assumed that @buf is a pointer into a PAGE_SIZE area and that * sufficient storage remains at @buf to accommodate the * bitmap_print_to_pagebuf() output. */intbitmap_print_to_pagebuf(boollist,char*buf,constunsignedlong*maskp,intnmaskbits){ptrdiff_tlen=PTR_ALIGN(buf+PAGE_SIZE-1,PAGE_SIZE)-buf;intn=0;if(len>1)n=list?scnprintf(buf,len,"%*pbl\n",nmaskbits,maskp):scnprintf(buf,len,"%*pb\n",nmaskbits,maskp);returnn;}EXPORT_SYMBOL(bitmap_print_to_pagebuf);/** * __bitmap_parselist - convert list format ASCII string to bitmap * @buf: read nul-terminated user string from this buffer * @buflen: buffer size in bytes. If string is smaller than this * then it must be terminated with a \0. * @is_user: location of buffer, 0 indicates kernel space * @maskp: write resulting mask here * @nmaskbits: number of bits in mask to be written * * Input format is a comma-separated list of decimal numbers and * ranges. Consecutively set bits are shown as two hyphen-separated * decimal numbers, the smallest and largest bit numbers set in * the range. * * Returns 0 on success, -errno on invalid input strings. * Error values: * %-EINVAL: second number in range smaller than first * %-EINVAL: invalid character in string * %-ERANGE: bit number specified too large for mask */staticint__bitmap_parselist(constchar*buf,unsignedintbuflen,intis_user,unsignedlong*maskp,intnmaskbits){unsigneda,b;intc,old_c,totaldigits;constchar__user__force*ubuf=(constchar__user__force*)buf;intat_start,in_range;totaldigits=c=0;bitmap_zero(maskp,nmaskbits);do{at_start=1;in_range=0;a=b=0;/* Get the next cpu# or a range of cpu#'s */while(buflen){old_c=c;if(is_user){if(__get_user(c,ubuf++))return-EFAULT;}elsec=*buf++;buflen--;if(isspace(c))continue;/* * If the last character was a space and the current * character isn't '\0', we've got embedded whitespace. * This is a no-no, so throw an error. */if(totaldigits&&c&&isspace(old_c))return-EINVAL;/* A '\0' or a ',' signal the end of a cpu# or range */if(c=='\0'||c==',')break;if(c=='-'){if(at_start||in_range)return-EINVAL;b=0;in_range=1;continue;}if(!isdigit(c))return-EINVAL;b=b*10+(c-'0');if(!in_range)a=b;at_start=0;totaldigits++;}if(!(a<=b))return-EINVAL;if(b>=nmaskbits)return-ERANGE;if(!at_start){while(a<=b){set_bit(a,maskp);a++;}}}while(buflen&&c==',');return0;}intbitmap_parselist(constchar*bp,unsignedlong*maskp,intnmaskbits){char*nl=strchrnul(bp,'\n');intlen=nl-bp;return__bitmap_parselist(bp,len,0,maskp,nmaskbits);}EXPORT_SYMBOL(bitmap_parselist);/** * bitmap_parselist_user() * * @ubuf: pointer to user buffer containing string. * @ulen: buffer size in bytes. If string is smaller than this * then it must be terminated with a \0. * @maskp: pointer to bitmap array that will contain result. * @nmaskbits: size of bitmap, in bits. * * Wrapper for bitmap_parselist(), providing it with user buffer. * * We cannot have this as an inline function in bitmap.h because it needs * linux/uaccess.h to get the access_ok() declaration and this causes * cyclic dependencies. */intbitmap_parselist_user(constchar__user*ubuf,unsignedintulen,unsignedlong*maskp,intnmaskbits){if(!access_ok(VERIFY_READ,ubuf,ulen))return-EFAULT;return__bitmap_parselist((constchar__force*)ubuf,ulen,1,maskp,nmaskbits);}EXPORT_SYMBOL(bitmap_parselist_user);/** * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap * @buf: pointer to a bitmap * @pos: a bit position in @buf (0 <= @pos < @nbits) * @nbits: number of valid bit positions in @buf * * Map the bit at position @pos in @buf (of length @nbits) to the * ordinal of which set bit it is. If it is not set or if @pos * is not a valid bit position, map to -1. * * If for example, just bits 4 through 7 are set in @buf, then @pos * values 4 through 7 will get mapped to 0 through 3, respectively, * and other @pos values will get mapped to -1. When @pos value 7 * gets mapped to (returns) @ord value 3 in this example, that means * that bit 7 is the 3rd (starting with 0th) set bit in @buf. * * The bit positions 0 through @bits are valid positions in @buf. */staticintbitmap_pos_to_ord(constunsignedlong*buf,unsignedintpos,unsignedintnbits){if(pos>=nbits||!test_bit(pos,buf))return-1;return__bitmap_weight(buf,pos);}/** * bitmap_ord_to_pos - find position of n-th set bit in bitmap * @buf: pointer to bitmap * @ord: ordinal bit position (n-th set bit, n >= 0) * @nbits: number of valid bit positions in @buf * * Map the ordinal offset of bit @ord in @buf to its position in @buf. * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord * >= weight(buf), returns @nbits. * * If for example, just bits 4 through 7 are set in @buf, then @ord * values 0 through 3 will get mapped to 4 through 7, respectively, * and all other @ord values returns @nbits. When @ord value 3 * gets mapped to (returns) @pos value 7 in this example, that means * that the 3rd set bit (starting with 0th) is at position 7 in @buf. * * The bit positions 0 through @nbits-1 are valid positions in @buf. */unsignedintbitmap_ord_to_pos(constunsignedlong*buf,unsignedintord,unsignedintnbits){unsignedintpos;for(pos=find_first_bit(buf,nbits);pos<nbits&&ord;pos=find_next_bit(buf,nbits,pos+1))ord--;returnpos;}/** * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap * @dst: remapped result * @src: subset to be remapped * @old: defines domain of map * @new: defines range of map * @nbits: number of bits in each of these bitmaps * * Let @old and @new define a mapping of bit positions, such that * whatever position is held by the n-th set bit in @old is mapped * to the n-th set bit in @new. In the more general case, allowing * for the possibility that the weight 'w' of @new is less than the * weight of @old, map the position of the n-th set bit in @old to * the position of the m-th set bit in @new, where m == n % w. * * If either of the @old and @new bitmaps are empty, or if @src and * @dst point to the same location, then this routine copies @src * to @dst. * * The positions of unset bits in @old are mapped to themselves * (the identify map). * * Apply the above specified mapping to @src, placing the result in * @dst, clearing any bits previously set in @dst. * * For example, lets say that @old has bits 4 through 7 set, and * @new has bits 12 through 15 set. This defines the mapping of bit * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other * bit positions unchanged. So if say @src comes into this routine * with bits 1, 5 and 7 set, then @dst should leave with bits 1, * 13 and 15 set. */voidbitmap_remap(unsignedlong*dst,constunsignedlong*src,constunsignedlong*old,constunsignedlong*new,unsignedintnbits){unsignedintoldbit,w;if(dst==src)/* following doesn't handle inplace remaps */return;bitmap_zero(dst,nbits);w=bitmap_weight(new,nbits);for_each_set_bit(oldbit,src,nbits){intn=bitmap_pos_to_ord(old,oldbit,nbits);if(n<0||w==0)set_bit(oldbit,dst);/* identity map */elseset_bit(bitmap_ord_to_pos(new,n%w,nbits),dst);}}EXPORT_SYMBOL(bitmap_remap);/** * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit * @oldbit: bit position to be mapped * @old: defines domain of map * @new: defines range of map * @bits: number of bits in each of these bitmaps * * Let @old and @new define a mapping of bit positions, such that * whatever position is held by the n-th set bit in @old is mapped * to the n-th set bit in @new. In the more general case, allowing * for the possibility that the weight 'w' of @new is less than the * weight of @old, map the position of the n-th set bit in @old to * the position of the m-th set bit in @new, where m == n % w. * * The positions of unset bits in @old are mapped to themselves * (the identify map). * * Apply the above specified mapping to bit position @oldbit, returning * the new bit position. * * For example, lets say that @old has bits 4 through 7 set, and * @new has bits 12 through 15 set. This defines the mapping of bit * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other * bit positions unchanged. So if say @oldbit is 5, then this routine * returns 13. */intbitmap_bitremap(intoldbit,constunsignedlong*old,constunsignedlong*new,intbits){intw=bitmap_weight(new,bits);intn=bitmap_pos_to_ord(old,oldbit,bits);if(n<0||w==0)returnoldbit;elsereturnbitmap_ord_to_pos(new,n%w,bits);}EXPORT_SYMBOL(bitmap_bitremap);/** * bitmap_onto - translate one bitmap relative to another * @dst: resulting translated bitmap * @orig: original untranslated bitmap * @relmap: bitmap relative to which translated * @bits: number of bits in each of these bitmaps * * Set the n-th bit of @dst iff there exists some m such that the * n-th bit of @relmap is set, the m-th bit of @orig is set, and * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. * (If you understood the previous sentence the first time your * read it, you're overqualified for your current job.) * * In other words, @orig is mapped onto (surjectively) @dst, * using the map { <n, m> | the n-th bit of @relmap is the * m-th set bit of @relmap }. * * Any set bits in @orig above bit number W, where W is the * weight of (number of set bits in) @relmap are mapped nowhere. * In particular, if for all bits m set in @orig, m >= W, then * @dst will end up empty. In situations where the possibility * of such an empty result is not desired, one way to avoid it is * to use the bitmap_fold() operator, below, to first fold the * @orig bitmap over itself so that all its set bits x are in the * range 0 <= x < W. The bitmap_fold() operator does this by * setting the bit (m % W) in @dst, for each bit (m) set in @orig. * * Example [1] for bitmap_onto(): * Let's say @relmap has bits 30-39 set, and @orig has bits * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, * @dst will have bits 31, 33, 35, 37 and 39 set. * * When bit 0 is set in @orig, it means turn on the bit in * @dst corresponding to whatever is the first bit (if any) * that is turned on in @relmap. Since bit 0 was off in the * above example, we leave off that bit (bit 30) in @dst. * * When bit 1 is set in @orig (as in the above example), it * means turn on the bit in @dst corresponding to whatever * is the second bit that is turned on in @relmap. The second * bit in @relmap that was turned on in the above example was * bit 31, so we turned on bit 31 in @dst. * * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, * because they were the 4th, 6th, 8th and 10th set bits * set in @relmap, and the 4th, 6th, 8th and 10th bits of * @orig (i.e. bits 3, 5, 7 and 9) were also set. * * When bit 11 is set in @orig, it means turn on the bit in * @dst corresponding to whatever is the twelfth bit that is * turned on in @relmap. In the above example, there were * only ten bits turned on in @relmap (30..39), so that bit * 11 was set in @orig had no affect on @dst. * * Example [2] for bitmap_fold() + bitmap_onto(): * Let's say @relmap has these ten bits set: * 40 41 42 43 45 48 53 61 74 95 * (for the curious, that's 40 plus the first ten terms of the * Fibonacci sequence.) * * Further lets say we use the following code, invoking * bitmap_fold() then bitmap_onto, as suggested above to * avoid the possibility of an empty @dst result: * * unsigned long *tmp; // a temporary bitmap's bits * * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); * bitmap_onto(dst, tmp, relmap, bits); * * Then this table shows what various values of @dst would be, for * various @orig's. I list the zero-based positions of each set bit. * The tmp column shows the intermediate result, as computed by * using bitmap_fold() to fold the @orig bitmap modulo ten * (the weight of @relmap). * * @orig tmp @dst * 0 0 40 * 1 1 41 * 9 9 95 * 10 0 40 (*) * 1 3 5 7 1 3 5 7 41 43 48 61 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 * 0 9 18 27 0 9 8 7 40 61 74 95 * 0 10 20 30 0 40 * 0 11 22 33 0 1 2 3 40 41 42 43 * 0 12 24 36 0 2 4 6 40 42 45 53 * 78 102 211 1 2 8 41 42 74 (*) * * (*) For these marked lines, if we hadn't first done bitmap_fold() * into tmp, then the @dst result would have been empty. * * If either of @orig or @relmap is empty (no set bits), then @dst * will be returned empty. * * If (as explained above) the only set bits in @orig are in positions * m where m >= W, (where W is the weight of @relmap) then @dst will * once again be returned empty. * * All bits in @dst not set by the above rule are cleared. */voidbitmap_onto(unsignedlong*dst,constunsignedlong*orig,constunsignedlong*relmap,unsignedintbits){unsignedintn,m;/* same meaning as in above comment */if(dst==orig)/* following doesn't handle inplace mappings */return;bitmap_zero(dst,bits);/* * The following code is a more efficient, but less * obvious, equivalent to the loop: * for (m = 0; m < bitmap_weight(relmap, bits); m++) { * n = bitmap_ord_to_pos(orig, m, bits); * if (test_bit(m, orig)) * set_bit(n, dst); * } */m=0;for_each_set_bit(n,relmap,bits){/* m == bitmap_pos_to_ord(relmap, n, bits) */if(test_bit(m,orig))set_bit(n,dst);m++;}}EXPORT_SYMBOL(bitmap_onto);/** * bitmap_fold - fold larger bitmap into smaller, modulo specified size * @dst: resulting smaller bitmap * @orig: original larger bitmap * @sz: specified size * @nbits: number of bits in each of these bitmaps * * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. * Clear all other bits in @dst. See further the comment and * Example [2] for bitmap_onto() for why and how to use this. */voidbitmap_fold(unsignedlong*dst,constunsignedlong*orig,unsignedintsz,unsignedintnbits){unsignedintoldbit;if(dst==orig)/* following doesn't handle inplace mappings */return;bitmap_zero(dst,nbits);for_each_set_bit(oldbit,orig,nbits)set_bit(oldbit%sz,dst);}EXPORT_SYMBOL(bitmap_fold);/* * Common code for bitmap_*_region() routines. * bitmap: array of unsigned longs corresponding to the bitmap * pos: the beginning of the region * order: region size (log base 2 of number of bits) * reg_op: operation(s) to perform on that region of bitmap * * Can set, verify and/or release a region of bits in a bitmap, * depending on which combination of REG_OP_* flag bits is set. * * A region of a bitmap is a sequence of bits in the bitmap, of * some size '1 << order' (a power of two), aligned to that same * '1 << order' power of two. * * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). * Returns 0 in all other cases and reg_ops. */enum{REG_OP_ISFREE,/* true if region is all zero bits */REG_OP_ALLOC,/* set all bits in region */REG_OP_RELEASE,/* clear all bits in region */};staticint__reg_op(unsignedlong*bitmap,unsignedintpos,intorder,intreg_op){intnbits_reg;/* number of bits in region */intindex;/* index first long of region in bitmap */intoffset;/* bit offset region in bitmap[index] */intnlongs_reg;/* num longs spanned by region in bitmap */intnbitsinlong;/* num bits of region in each spanned long */unsignedlongmask;/* bitmask for one long of region */inti;/* scans bitmap by longs */intret=0;/* return value *//* * Either nlongs_reg == 1 (for small orders that fit in one long) * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) */nbits_reg=1<<order;index=pos/BITS_PER_LONG;offset=pos-(index*BITS_PER_LONG);nlongs_reg=BITS_TO_LONGS(nbits_reg);nbitsinlong=min(nbits_reg,BITS_PER_LONG);/* * Can't do "mask = (1UL << nbitsinlong) - 1", as that * overflows if nbitsinlong == BITS_PER_LONG. */mask=(1UL<<(nbitsinlong-1));mask+=mask-1;mask<<=offset;switch(reg_op){caseREG_OP_ISFREE:for(i=0;i<nlongs_reg;i++){if(bitmap[index+i]&mask)gotodone;}ret=1;/* all bits in region free (zero) */break;caseREG_OP_ALLOC:for(i=0;i<nlongs_reg;i++)bitmap[index+i]|=mask;break;caseREG_OP_RELEASE:for(i=0;i<nlongs_reg;i++)bitmap[index+i]&=~mask;break;}done:returnret;}/** * bitmap_find_free_region - find a contiguous aligned mem region * @bitmap: array of unsigned longs corresponding to the bitmap * @bits: number of bits in the bitmap * @order: region size (log base 2 of number of bits) to find * * Find a region of free (zero) bits in a @bitmap of @bits bits and * allocate them (set them to one). Only consider regions of length * a power (@order) of two, aligned to that power of two, which * makes the search algorithm much faster. * * Return the bit offset in bitmap of the allocated region, * or -errno on failure. */intbitmap_find_free_region(unsignedlong*bitmap,unsignedintbits,intorder){unsignedintpos,end;/* scans bitmap by regions of size order */for(pos=0;(end=pos+(1U<<order))<=bits;pos=end){if(!__reg_op(bitmap,pos,order,REG_OP_ISFREE))continue;__reg_op(bitmap,pos,order,REG_OP_ALLOC);returnpos;}return-ENOMEM;}EXPORT_SYMBOL(bitmap_find_free_region);/** * bitmap_release_region - release allocated bitmap region * @bitmap: array of unsigned longs corresponding to the bitmap * @pos: beginning of bit region to release * @order: region size (log base 2 of number of bits) to release * * This is the complement to __bitmap_find_free_region() and releases * the found region (by clearing it in the bitmap). * * No return value. */voidbitmap_release_region(unsignedlong*bitmap,unsignedintpos,intorder){__reg_op(bitmap,pos,order,REG_OP_RELEASE);}EXPORT_SYMBOL(bitmap_release_region);/** * bitmap_allocate_region - allocate bitmap region * @bitmap: array of unsigned longs corresponding to the bitmap * @pos: beginning of bit region to allocate * @order: region size (log base 2 of number of bits) to allocate * * Allocate (set bits in) a specified region of a bitmap. * * Return 0 on success, or %-EBUSY if specified region wasn't * free (not all bits were zero). */intbitmap_allocate_region(unsignedlong*bitmap,unsignedintpos,intorder){if(!__reg_op(bitmap,pos,order,REG_OP_ISFREE))return-EBUSY;return__reg_op(bitmap,pos,order,REG_OP_ALLOC);}EXPORT_SYMBOL(bitmap_allocate_region);/** * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order. * @dst: destination buffer * @src: bitmap to copy * @nbits: number of bits in the bitmap * * Require nbits % BITS_PER_LONG == 0. */#ifdef __BIG_ENDIANvoidbitmap_copy_le(unsignedlong*dst,constunsignedlong*src,unsignedintnbits){unsignedinti;for(i=0;i<nbits/BITS_PER_LONG;i++){if(BITS_PER_LONG==64)dst[i]=cpu_to_le64(src[i]);elsedst[i]=cpu_to_le32(src[i]);}}EXPORT_SYMBOL(bitmap_copy_le);#endif